Method of utilizing crystal oscillators to effect frequency selection



- May 18, 1948. J. M. GLESSNER 2,441,570

METHOD OF UTILIZING CRYSTAL OSCILLATORS T0 EFFECT FREQUENCY SELECTIONFiled Sept. 4, 1945 qIIJIIIIIlIJ I ll m L w wwmmwk UL E v M1 vs ro maxM. 'GLESS/VER ATTORNEY Patented May 18, 1948 METHOD OF UTILIZING CRYSTALOSCILLA- TORS TO EFFECT FREQUENCY SELECTION Jack M. Glessner, Dayton,Ohio Application September 4, 1945, Serial No. 614,342

2 Claims. (01. 250-36) (Granted under the act of March 3, 1883, as

The invention described herein may be manufactured and used by or forthe Government for governmental purposes, without the payment to me ofany royalty thereon.

This invention relates to a method and means for controlling frequencyselection in crystal oscillators and is directed particularly to asystem whereby frequency selection is affected by any one of a number ofremote control stations.

One object of the present invention is to provide a novel system offrequency selection in which any one of a plurality of crystals maycontrol the oscillation frequency.

Another object is to provide a system of frequency selection in which aplurality of crystals in addition to the controlling crystal may be keptin the oscillator circuit without affecting the operation of the system.

Further objects and advantages of the system will appear in thespecification and claims and in the appended drawing in which:

Fig. 1 shows a typical crystal controlled oscillator circuit in which aplurality of crystals are employed.

Fig. 2 shows a system of frequency selection utilizing a plurality ofcrystals and remote control stations.

The invention herein disclosed depends on a phenomena which may bedescribed as follows: when a second frequency determining element suchas a quartz crystal or equivalent circuit is connected in parallel witha first frequency determining element (usually a quartz crystal) of anoscillator circuit already oscillating in response to the first crystalno appreciable change in frequency occurs. Thus it is apparent that theaddition of a second crystal does not rob the first crystal of itsfrequency determining power provided the first crystal is alreadyoscillating when the second crystal is added to the circuit. Inexperiments I have performed it appears wellestablished that theaddition of up to a total of six crystals does not alter the operation;the first crystal to oscillate maintains its control over the circuitregardless of the addition of the other crystals. There is every reasonto believe that the system may be extended to include any practicalnumber of crystals.

In Fig. 1 a plurality of crystals I to 6 are arranged with theirrespective switches II to Hi so that any number of crystals may beplaced in the oscillator circuit which includes triode I, inductance 9,variable capacitor 8 and battery III. In the oscillator circuitillustrated in the drawings, well-known means may be used to remotelyamended April 30, 1928; 3'70 0. G. 757) vary capacitor 8 to adjust thetuned circuit as the frequency of oscillation is shifted with the use ofdifferent crystals. However, an untuned type of oscillator may besubstituted, in which the crystal is the sole frequency determiningelement and no other adjustment for oscillation is required over a widefrequency range. An example of this type of oscillator is found inPatent No. 2,240,450, issued to John M. Wolfskill. If all the switchesare closed before the oscillator circuit is closed one particularcrystal will always predominate the others and practicallyinstantaneously take control of the circuit and the latter willoscillate at the frequency determined by this one crystal. This randomstarting of oscillation by the same crystal every time is due, mostprobably, to the activity of the particular crystal being greater thanthat of any of the others.

Furthermore, if switch II is closed and the oscillator started crystal Iwill control the frequency. If, while the circuit is still oscillating,all the switches I2 to It are closed there will be no appreciable changein the frequency of the circuit other than that due to the introductionof slight additional circuit resistance and reactance inherent in theadded crystals, crystal holders, switches, and wiring. If now, withcrystal I controlling the oscillation and with all switches I I to Itclosed, all the switches are opened except one, for example, switch I4,and the opened switches are immediately reclosed it will be found thatthe frequency of the circuit has been shifted and is now determined bycrystal 4. Thus the arrangement shown in Fig. 1 is suitable as a meansfor controlling frequency selection and switches I I to It could beoperated in any suitable fashion, such as by relays.

Fig. 2 shows a system such as might be used in aircraft installationwhereby frequency selection may be controlled by any one of a number ofremote control stations. In this figure crystals I to 6 are providedwith switches II to I6 respectively, the switches being operable bysolenoids or electromagnetic coils 2| to 26. The representativeoscillator circuit includes triode 1, variable capacitor 8, inductance 9and battery I0. Switches II to I6 are ordinarily closed, as shown, andare opened only upon energization of solenoids or electromagnets 2i to26. The power source for operation'of the relays is battery 20 and inthe system of Fig. 2 any crystal may be made the controlling elementfrom any one of remote control stations 31, 51 and 11.

Remote control station No. 1, shown at 31, includes a rotatable switchmember 41 in the form of a split ring and is connected to one terminalof the power source for the relays, which may be any suitable source,although battery 20 has been shown for convenience. Ring 41 is providedwith a radial non-conducting portion 48 which is slightly wider than,and operates with, switch contacts 4| to 46 inclusive.

Contacts 4| to 46 are in the circuits of relays 2| to 28 respectively tocontrol the opening or closing of relay contacts II to Hi. In theposition shown in remote control station No. 1, contact 43 of relay 23which controls crystal '3 is in non-conducting position.

Between contacts 4| to 46 and relay coils 2| to 26 are a group of gangedpush button switches 3| to 35 respectively which can be closedsimultaneously by push button 30. With the rotary switch 41 in theposition shown, and assuming the oscilator circuit is energized,pressure on button 30 will close the circuits to relay coils 2|, 22,

24, 2.5 and 26, opening relay contacts ll, l2, l4,

l and I6 respectively and simultaneously, thereby removing crystals I,2, 4, 5 and (i from the oscillator circuit. Crystal 3 remains in thecircuit and controls the frequency of the oscillator. Releasing ofbutton 38 will cause switches 3| to 3.6 to open, .deenergizing relays2i, 22, 24, 25 and Z6 and placing all crystals in the circuit, whichwill continue to oscillate the frequency set by crystal ,3.

Switch 41 may be rotated to any other position and button so may bedepressed to change the frequency to that of any other crystal. Likewiseremote control stations 2 and 3, indicated at ST and ll respectively,and which are in parallel with station No. 1 may be set to operate anycrystal by rotating switches 61 and 31 and depressing buttons 50 orrespectively. In the positions shown in Fig. .2 depression of buttons 50or m will cause crystals 6 and 2, respectively, to control theoscillator frequency. In control station No. 2 contacts 5| to 65, gangedpush button switches .51 to 55, and connection 89 correspond to similarelements in station No. 1, and likewise contacts 8| to 8B, push buttonswitches H to it and connection 39 in control station No. 3.

The frequency selection system described herein oifers the advantage ofpermitting relatively simple switching .from any one of any number ofremote switching positions. As many remote operating positions asdesired may be added in parallel connection with the remote controlstations already in use without the necessity of altering .thetransmitter or receiver circuit, as the case may be, and Without cuttingseries circuits into the wiring of the apparatus or of any of the remotecontrol stations. Remote control at any station is possible, regardlessof the previous tuning affected by any other remote control station.

This is achieved with a simplified relay circuit giving control fromvarious positions independent of prior frequency selection.

It is apparent that the control of frequencies in accordance with theinvention as set forth above could be accomplished in many ways bydifferent arrangements of combinations of parts, the specificembodiments shown being presented by way of example only. Therefore I donot intend my invention to be limited in scope or extent except inaccordance with the appended claims.

I claim:

1. A remote control system, comprising a plurality of relays each havingan actuating coil and a circuit closing contact, each of said contactsopening a circuit when said coils are energized, said coils beingconnected in parallel, a direct current source, a plurality of switchingmeans simultaneously closed by one control, one end of each of saidcoils being connected to a first terminal of said source, the other endbeing connected to one pole of each of said switching means, the otherpole of each of said switching means being connected to one of aplurality of brushes, a selector means comprising electricallyconductive split ring connecting said brushes to the second terminal ofsaid source, means to rotate said selector means whereby a selectedbrush connected to any one of said coils through said switching meansmay be disposed in the split portion of said ring and all other brushescontact said ring, whereby when said control closes said switches all ofsaid coils are energized except the one connected to the'brush disposedin said split portion and all of said contacts open their circuitsexcept the contact in circuit with said selected brush.

2. A remote control system as set forth in claim 1, wherein each of saidcontacts opens a crystal electrode when said coils are energized, saidelectrode connecting said crystal in parallel with a plurality ofcrystals in a variable frequency crystal controlled oscillator.

JACK M. GLESSNER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,984,424 Osnos Dec. ,18, 19342,073,117 Parkin Mar. 9, 1937 2,240,450 Wolfskill Apr. 29, 1941 FOREIGNPATENTS Number Country Date 314,089 Great Britain May 8, 1930

